This invention is directed to drip chambers for infusion and transfusion apparatus, in which the drip chambers comprise several rigidly interconnected parts.
Such drip chambers generally are formed of at least two-parts, the so-called piercing mandrel or grooved tubular piercing needle and the housing of the liquid chamber. The parts can consist of different material, but generally are made of a plastic composition material, and the parts are rigidly connected with each other in various ways at their junctions. The manufacture of the known joints presents difficulties.
Thus, not all materials of which the apparatus is made are suitable for adhesive joints. If the parts are to be cemented with each other at their junctions, one is confined to certain materials which are disadvantageous, however, for the manufacture and the use of the parts of the apparatus for other reasons.
The same holds generally true for welded joints, in that these too permit the selection of only a few materials. Additionally, with welded joints, there is a risk of lack of tightness in the production of the joint.
It is also known to spray the junction between the parts with plastic, but this method is very complicated and consequently expensive. Also, with this method, there is the risk of lack of tightness of the junctions in mass production.
Summarizing, it can be said that known types of joints for drip chambers for infusion and transfusion apparatus are either expensive or have only a limited application, or that there is a risk of the junction between the parts not being tight and thereby not forming a liquid tight seal between the parts.